Rebar tying tool

ABSTRACT

A rebar tying tool may be configured to tie rebars with a wire. The rebar tying tool may include: a contact member configured to contact the wire during a tying operation in which the rebar tying tool ties the rebars with the wire. The contact member may include: a base; and a surface layer covering at least a part of a surface of the base and configured to contact the wire during the tying operation. Hardness of the surface layer may be higher than hardness of the base.

REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2022-098161, filed on Jun. 17, 2022, the entire contents of which are hereby incorporated by reference into the present application.

TECHNICAL FIELD

The disclosure herein relates to rebar tying tools.

BACKGROUND ART

Japanese Patent Application Publication No. 2004-59017 describes a rebar tying tool. The rebar tying tool ties rebars with a wire. The rebar tying tool includes a first contact member configured to contact the wire during a tying operation in which the rebar tying tool ties the rebars with the wire. Further, the rebar tying tool includes a second contact member and a third contact member configured to contact the second contact member and move relative to the second contact member during the tying operation.

DESCRIPTION

Repeated tying operations by the above-described rebar tying tool may result in wear of the first contact member due to its contact with the wire, and may also result in wear of the second and third contact members due to them rubbing against each other. The disclosure herein provides techniques that can reduce wear of a contact member even under repeated tying operations.

A rebar tying tool disclosed herein may be configured to tie rebars with a wire. The rebar tying tool may comprise a contact member configured to contact the wire during a tying operation in which the rebar tying tool ties the rebars with the wire. The contact member may comprise a base; and a surface layer covering at least a part of a surface of the base and configured to contact the wire during the tying operation. Hardness of the surface layer may be higher than hardness of the base.

According to the configuration above, the hardness of the surface layer is higher than the hardness of the base, and thus the surface layer of the contact member is less likely to wear out when contacting the wire, as compared with a configuration in which the contact member comprises only the base. Thus, wear of the contact member can be reduced even under repeated tying operations.

A rebar tying tool disclosed herein may be configured to tie rebars with a wire. The rebar tying tool may comprise a first contact member; and a second contact member configured to contact the first contact member and move relative to the first contact member during a tying operation in which the rebar tying tool ties the rebars with the wire. The first contact member may comprise a first base; and a first surface layer covering at least a part of a surface of the first base. The second contact member may comprise a second base; and a second surface layer covering at least a part of a surface of the second base and configured to contact the first surface layer during the tying operation. Hardness of the first surface layer may be higher than hardness of the first base. Hardness of the second surface layer may be higher than hardness of the second base.

According to the configuration above, the hardness of the first surface layer is higher than the hardness of the first base and the hardness of the second surface layer is higher than the hardness of the second base, and thus the first surface layer of the first contact member and the second surface layer of the second contact member are less likely to wear out when rubbing against each other, as compared with a configuration in which the first contact member comprises only the first base and the second contact member comprises only the second base. Thus, wear of the first and second contact members can be reduced even under repeated tying operations.

A rebar tying tool disclosed herein may be configured to tie rebars with a wire. The rebar tying tool may comprise a feed roller configured to feed the wire toward the rebars when the rebar tying tool ties the rebars with the wire. Hardness of a surface layer of the feed roller may be equal to or more than 900 HV. Herein, HV represents Vickers hardness.

The feed roller contacts the wire when feeding the wire toward the rebars. According to the configuration above, the hardness of the surface layer of the feed roller is equal to or more than 900 HV, and thus the surface layer of the feed roller is less likely to wear out when contacting the wire. Thus, wear of the feed roller can be reduced even under repeated tying operations.

A rebar tying tool disclosed herein may be configured to tie rebars with a wire. The rebar tying tool may comprise a first feed roller configured to contact the wire and be rotated by a motor when the wire is fed toward the rebars; and a second feed roller configured to contact the wire when the wire is fed toward the rebars. The wire may be clamped between the first feed roller and the second feed roller and fed toward the rebars by rotation of the first feed roller. The first feed roller may comprise a groove that the wire passes through when the wire is fed toward the rebars. Hardness of the first feed roller in the groove may be equal to or more than 1000 HV.

According to the configuration above, the hardness of the first feed roller in the groove is equal to or more than 1000 HV, and thus the first feed roller is less likely to wear out when contacting the wire in the groove. Thus, wear of the first feed roller in the groove can be reduced even under repeated tying operations.

FIG. 1 is a perspective view of a rebar tying tool 2 according to an embodiment, as viewed from the upper front right side.

FIG. 2 is a perspective view of the rebar tying tool 2 according to the embodiment, as viewed from the upper rear left side.

FIG. 3 is a side view illustrating an internal structure of the rebar tying tool 2 according to the embodiment.

FIG. 4 is a perspective view of a feed unit 34 according to the embodiment.

FIG. 5 is a cross-sectional view of the rebar tying tool 2 according to the embodiment, in the vicinity of a guide part 42.

FIG. 6 is an exploded perspective view of an upper curl guide 66 according to the embodiment.

FIG. 7 is a side view of a cutter unit 36 and a twisting unit 38 according to the embodiment before the cutter unit 36 cuts a wire W.

FIG. 8 is a side view of the cutter unit 36 and the twisting unit 38 according to the embodiment after the cutter unit 36 has cut the wire W.

FIG. 9 is a perspective view of the twisting unit 38 according to the embodiment.

FIG. 10 is a perspective view of a screw shaft 126 and a ball 128 according to the embodiment.

FIG. 11 is a cross-sectional view of a contact member 150 according to the embodiment.

FIG. 12 is a perspective view of a first feed gear 58 according to the embodiment.

FIG. 13 is a cross-sectional view of the first feed gear 58 according to the embodiment.

FIG. 14 is a cross-sectional view of a first contact member 152 and a second contact member 154 according to the embodiment.

FIG. 15 is a cross-sectional view of the first feed gear 58 and a second feed gear 60 according to the embodiment.

Representative, non-limiting examples of the present disclosure will now be described in further detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the present disclosure. Furthermore, each of the additional features and teachings disclosed below may be utilized separately or in conjunction with other features and teachings to provide improved rebar tying tools, as well as methods for using and manufacturing the same.

Moreover, combinations of features and steps disclosed in the following detailed description may not be necessary to practice the present disclosure in the broadest sense, and are instead taught merely to particularly describe representative examples of the present disclosure. Furthermore, various features of the above-described and below-described representative examples, as well as the various independent and dependent claims, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.

All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.

A rebar tying tool disclosed herein may be configured to tie rebars with a wire. The rebar tying tool may comprise a contact member configured to contact the wire during a tying operation in which the rebar tying tool ties the rebars with the wire. The contact member may comprise a base; and a surface layer covering at least a part of a surface of the base and configured to contact the wire during the tying operation. Hardness of the surface layer may be higher than hardness of the base.

In one or more embodiments, the surface layer may be constituted of a ceramic material.

Generally, ceramic materials have higher hardness compared with other materials. According to the configuration above, wear of the contact member can be further reduced even under repeated tying operations.

In one or more embodiments, the ceramic material may include tungsten carbide.

Generally, tungsten carbide has higher hardness compared with other materials. According to the configuration above, wear of the contact member can be further reduced even under repeated tying operations.

In one or more embodiments, a thickness of the surface layer may be equal to or more than 10 micrometers.

If the thickness of the surface layer is less than 10 micrometers, the surface layer may be damaged by a force it receives from the wire. According to the configuration above, it is possible to suppress the surface layer from being damaged by the force it receives from the wire.

In one or more embodiments, the thickness of the surface layer may be equal to or less than 200 micrometers.

According to the configuration above, separation of the surface layer from the base can be suppressed even under repeated tying operations.

In one or more embodiments, the hardness of the surface layer may be equal to or more than 900 HV.

Generally, the contact member is likely to wear out with the use of a wire having a larger diameter. According to the configuration above, wear of the contact member can be further reduced even when a large-diameter wire is used.

In one or more embodiments, the rebar tying tool may further comprise a feed motor; and a feed roller configured to rotate with rotation of the feed motor and feed the wire toward the rebars. The contact member may form the feed roller.

Generally, the feed roller is likely to wear out because it feeds the wire toward rebars. According to the configuration above, wear of the feed roller can be reduced even under repeated tying operations.

In one or more embodiments, the rebar tying tool may further comprise a cutter configured to cut the wire during the tying operation. The contact member may form the cutter.

Generally, the cutter is likely to wear out because it is pressed hard against the wire to cut it. According to the configuration above, wear of the cutter can be reduced even under repeated tying operations.

A rebar tying tool disclosed herein may be configured to tie rebars with a wire. The rebar tying tool may comprise a first contact member; and a second contact member configured to contact the first contact member and move relative to the first contact member during a tying operation in which the rebar tying tool ties the rebars with the wire. The first contact member may comprise a first base; and a first surface layer covering at least a part of a surface of the first base. The second contact member may comprise a second base; and a second surface layer covering at least a part of a surface of the second base and configured to contact the first surface layer during the tying operation. Hardness of the first surface layer may be higher than hardness of the first base. Hardness of the second surface layer may be higher than hardness of the second base.

In one or more embodiments, each of the first surface layer and the second surface layer may be constituted of a ceramic material.

Generally, ceramic materials have higher hardness compared with other materials.

According to the configuration above, wear of the first and second contact members can be further reduced even under repeated tying operations.

In one or more embodiments, the ceramic material may include tungsten carbide.

Generally, tungsten carbide has higher hardness compared with other materials. According to the configuration above, wear of the first and second contact members can be further reduced even under repeated tying operations.

In one or more embodiments, each of a thickness of the first surface layer and a thickness of the second surface layer may be equal to or more than 10 micrometers.

If the thicknesses of the first and second surface layers are less than 10 micrometers, the first and second surface layers may be damaged by them contacting each other during the tying operation. According to the configuration above, it is possible to suppress the first and second surface layers from being damaged.

In one or more embodiments, each of the thickness of the first surface layer and the thickness of the second surface layer may be equal to or less than 200 micrometers.

According to the configuration above, separation of the first surface layer from the first base and separation of the second surface layer from the second base can be suppressed even under repeated tying operations.

In one or more embodiments, each of the hardness of the first surface layer and the hardness of the second surface layer may be equal to or more than 900 HV.

Generally, a larger force acts between the first and second contact members with use of a wire having a larger diameter. According to the configuration above, wear of the first and second contact members can be further reduced even when a large-diameter wire is used.

In one or more embodiments, the rebar tying tool may further comprise a cutter unit configured to cut the wire during the tying operation. The cutter unit may comprise the first contact member and the second contact member.

The cutter unit is pressed hard against the wire to cut it, and thus a large force acts between the first and second contact members. Therefore, the first and second contact members of the cutter unit are likely to wear out faster in general. According to the configuration above, wear of the first and second contact members can be reduced even under repeated tying operations.

A rebar tying tool disclosed herein may be configured to tie rebars with a wire. The rebar tying tool may comprise a feed roller configured to feed the wire toward the rebars when the rebar tying tool ties the rebars with the wire. Hardness of a surface layer of the feed roller may be equal to or more than 900 HV. Herein, HV represents Vickers hardness.

A rebar tying tool disclosed herein may be configured to tie rebars with a wire. The rebar tying tool may comprise a first feed roller configured to contact the wire and be rotated by a motor when the wire is fed toward the rebars; and a second feed roller configured to contact the wire when the wire is fed toward the rebars. The wire may be clamped between the first feed roller and the second feed roller and fed toward the rebars by rotation of the first feed roller. The first feed roller may comprise a groove that the wire passes through when the wire is fed toward the rebars. Hardness of the first feed roller in the groove may be equal to or more than 1000 HV.

EMBODIMENT

As illustrated in FIG. 1 , a rebar tying tool 2 is configured to tie a plurality of rebars R with a wire W. With the rebar tying tool 2, wires W with various diameters (e.g., with diameters from 0.5 mm to 2.5 mm) can be used depending on the diameter of rebars R used. For example, a wire W with a diameter of 1.6 mm or less (e.g., 0.8 mm) is used to tie rebars R with a small diameter of 16 mm or less (e.g., 16 mm), while a wire W with a diameter of 1.6 mm or more (e.g., 2.0 mm) is used to tie rebars R with a large diameter of more than 16 mm (e.g., 25 mm or 32 mm). Hereinafter, a longitudinal direction of a twisting unit 38 (see FIG. 3 ) will be termed a front-rear direction, a direction perpendicular to the front-rear direction will be termed an up-down direction, and a direction perpendicular to the front-rear direction and the up-down direction will be termed a right-left direction.

The rebar tying tool 2 comprises a body 4, a reel holder 6, and a battery pack B. The body 4 comprises a left body 8 defining an outer shape of the left half of the body 4, a right body 10 defining an outer shape of the right half of the body 4, and a motor cover 12 attached to an outer side of the right body 10. The left body 8 and the right body 10 are fixed with a plurality of screws S1. The right body 10 and the motor cover 12 are fixed with a plurality of screws S2.

The body 4 comprises a body housing 14, a grip 16, and a battery-mount part 18. The body housing 14, the grip 16, and the battery-mount part 18 are formed integrally. The grip 16 is gripped by a user. A trigger 20 is attached to an upper portion of a front surface of the grip 16. The battery pack B is detachably attachable to the battery-mount part 18.

The reel holder 6 is attached to a lower front portion of the body housing 14. As illustrated in FIG. 2 , the reel holder 6 can house a reel 24 therein. A wire W is wound around the reel 24. The reel 24 can be attached to and detached from the reel holder 6 when a cover 26 of the reel holder 6 is open.

As illustrated in FIG. 3 , the rebar tying tool 2comprises a control circuit board 30. The control circuit board 30 is housed within the battery-mount part 18. When the trigger 20 is pushed in, the control circuit board 30 causes the rebar tying tool 2 to perform a tying operation in which the rebars R are tied with the wire W.

The rebar tying tool 2 comprises a feed unit 34, a cutter unit 36, and a twisting unit 38. The feed unit 34 comprises a feed part 40 and a guide part 42. The feed part 40 is housed within a front portion of the body housing 14. The guide part 42 is positioned at the front portion of the body housing 14. The cutter unit 36 and the twisting unit 38 are housed within the body housing 14.

As illustrated in FIG. 4 , the feed part 40 comprises a feed motor 50, a reducer 52, a base member 54, a drive gear 56, a first feed gear 58, a second feed gear 60, a release lever 62, and a compression spring 64. The feed motor 50 is positioned on the right side of the right body 10 (see FIG. 1 ) and covered by the motor cover 12 (see FIG. 1 ). The feed motor 50 operates using electric power supplied from the battery pack B (see FIG. 1 ). The feed motor 50 is, for example, a brushless motor. The feed motor 50 is controlled by the control circuit board (see FIG. 3 ). The reducer 52 reduces a rotational speed of the feed motor 50 and transmits it to the drive gear 56.

The base member 54 is fixed to the body housing 14 (see FIG. 1 ). An outer circumferential surface of the first feed gear 58 meshes with an outer circumferential surface of the second feed gear 60. The first feed gear 58 is rotatably supported by the base member 54. The first feed gear 58 is rotated by the rotation of the drive gear 56. The first feed gear 58 includes a groove 58 a defined in its outer circumferential surface and extending in a full circle about a rotation axis. The first feed gear 58 contacts the wire W in the groove 58 a. The second feed gear 60 is rotatably supported by the release lever 62. The second feed gear 60 includes a groove 60 a defined in its outer circumferential surface and extending in a full circle about a rotation axis. The second feed gear 60 contacts the wire W in the groove 60 a.

The release lever 62 is pivotably supported by the base member 54. The compression spring 64 biases the release lever 62 in a direction in which the second feed gear 60 is brought closer to the first feed gear 58. Thus, the second feed gear 60 is pressed against the first feed gear 58. As a result, the wire W is clamped between the groove 58 a of the first feed gear 58 and the groove 60 a of the second feed gear 60. When the feed motor 50 rotates with the wire W clamped between the groove 58 a of the first feed gear 58 and the groove 60 a of the second feed gear 60, the wire W is moved.

As illustrated in FIG. 5 , the guide part 42 comprises an upper curl guide 66 and a lower curl guide 68. The upper curl guide 66 and the lower curl guide 68 project forward beyond a front end of the body housing 14.

As illustrated in FIG. 6 , the upper curl guide 66 comprises a first upper curl guide 70, a second upper curl guide 72, a third upper curl guide 74, and a front guide pin 76. The first upper curl guide 70 is fixed to the body housing 14 (see FIG. 1 ). A lower surface 70 a of a front portion of the first upper curl guide 70 includes an upwardly recessed curved surface. A first fixation hole 80 is defined near a front end of the first upper curl guide 70. The first fixation hole 80 penetrates the first upper curl guide 70 in its thickness direction.

The second upper curl guide 72 is interposed between the front portion of the first upper curl guide 70 and the third upper curl guide 74. A lower surface 72 a of the second upper curl guide 72 includes an upwardly recessed curved surface. The lower surface 72 a of the second upper curl guide 72 is positioned above the lower surface 70 a of the front portion of the first upper curl guide 70. A second fixation hole 82 is defined near a front end of the second upper curl guide 72. The second fixation hole 82 penetrates the second upper curl guide 72 in its thickness direction. The second fixation hole 82 is connected to the lower surface 72 a of the second upper curl guide 72.

The third upper curl guide 74 is positioned on the left side of the second upper curl guide 72. A lower surface 74 a of the third upper curl guide 74 includes an upwardly recessed curved surface. In the up-down direction, the lower surface 74 a of the third upper curl guide 74 is approximately at the same position as the lower surface 70 a of the front portion of the first upper curl guide 70. A right surface 74 b of the third upper curl guide 74 faces a left surface of the first upper curl guide 70. A third fixation hole 84 is defined near a front end of the third upper curl guide 74. The third fixation hole 84 penetrates the third upper curl guide 74 in its thickness direction.

The first fixation hole 80, the second fixation hole 82, and the third fixation hole 84 are aligned along the right-left direction. The front guide pin 76 is inserted in the first fixation hole 80, the second fixation hole 82, and the third fixation hole 84.

As illustrated in FIG. 5 , the upper curl guide 66 includes an upper wire passage 86. The upper wire passage 86 is defined by the left surface 70 b of the first upper curl guide 70, the lower surface 72 a of the second upper curl guide 72, and the right surface 74 b of the third upper curl guide 74 (see FIG. 6 ). The front guide pin 76 is partially positioned in the upper wire passage 86.

The lower curl guide 68 is positioned below the upper curl guide 66. The lower curl guide 68 is open upward. The lower curl guide 68 includes a lower wire passage 88.

When the feed motor 50 (see FIG. 4 ) rotates in a first direction D1 (see FIG. 4 ), the first feed gear 58 and the second feed gear 60 are rotated and feed the wire W toward the upper wire passage 86. The wire W, which has been fed into the upper wire passage 86, proceeds forward through the upper wire passage 86 while contacting the lower surface 72 a of the second upper curl guide 72. While proceeding though the upper wire passage 86, the wire W also contacts the front guide pin 76. As a result, a downward winding curl is imparted to the wire W. After passing through the upper wire passage 86, the wire W is guided into the lower wire passage 88. The wire W, which has been fed into the lower wire passage 88, proceeds rearward through the lower wire passage 88 and then is guided rearward and upward. Consequently, the wire W is wound around the rebars R. When the feed motor 50 rotates in a second direction D2 (see FIG. 4 ) opposite to the first direction D1 with a portion of the wire W near its tip end held by a holding unit 124 (see FIG. 9 ), which will be described later, the first feed gear 58 and the second feed gear 60 are rotated such that the wire W is pulled back toward the reel 24 (see FIG. 3 ). As a result, the diameter of the loop of the wire W around the rebars R is reduced and the wire is brought into contact the rebars R.

As illustrated in FIG. 7 , the cutter unit 36 comprises a base member 92, a guide member 93, a first cutter 94, a second cutter 96, a first lever member 98, a second lever member 100, a first shaft 102, a second shaft 104, a link member 106, a torsion spring 108, a connection pin 114, and a fixation pin 115.

The base member 92 is fixed to the body housing 14 (see FIG. 3 ) with a plurality of screws S3 (see FIG. 3 ). A front end of the base member 92 is fixed to the lower curl guide 68 with a screw S4 and a pin P1 (see FIG. 8 ).

As illustrated in FIG. 5 , the guide member 93 is positioned on the left side of the base member 92 near the front end of the base member 92. The base member 92 and the guide member 93 are fixed with a screw S5. The guide member 93 includes a guide hole 93 a. The width of the guide hole 93 a is gradually decreased from its lower end toward its upper end and then becomes constant from a certain point. The wire W fed by the first feed gear 58 and the second feed gear 60 (see FIG. 4 ) passes through the guide hole 93 a.

The first cutter 94, the second cutter 96, and the guide hole 93 a are positioned on a path the wire W follows from the feed part 40 toward the upper curl guide 66. The first cutter 94 is fixed to the base member 92 near a front end thereof. The first cutter 94 is immovable with respect to the body housing 14 (see FIG. 3 ). The first cutter 94 has a first cutter opening 110. The first cutter 94 is inserted in the second cutter 96. The second cutter 96 is supported by the first cutter 94 so as to be rotatable about the first cutter 94. The second cutter 96 is rotatable with respect to the body housing 14 (see FIG. 3 ). The second cutter 96 has a second cutter opening 112. Before the cutter unit 36 cuts the wire W, the first cutter opening 110 and the second cutter opening 112 communicate with each other. On the way from the feed part 40 to the upper curl guide 66, the wire W is guided by the guide hole 93 a to pass through the first cutter opening 110 and the second cutter opening 112. When the second cutter 96 rotates in a third direction D3 about the first cutter 94 in the state where the wire W is through the first cutter opening 110 and the second cutter opening 112, the first cutter 94 and the second cutter 96 contact the wire W and cut it.

As illustrated in FIG. 7 , the first lever member 98 and the second lever member 100 are fixed by the first shaft 102 and the second shaft 104. The first shaft 102 and the second shaft 104 are inserted in the first lever member 98 and the second lever member 100. The first shaft 102 is fixed to the base member 92, and the first lever member 98 and the second lever member 100 rotate about the first shaft 102. The second shaft 104 is inserted in a lower end portion of the first lever member 98 and a lower end portion of the second lever member 100. When the first lever member 98 and the second lever member 100 rotate about the first shaft 102, the second shaft 104 moves along with the first lever member 98 and the second lever member 100. The first lever member 98 comprises a first projection 98 a configured to be manipulated by the twisting unit 38. The second lever member 100 comprises a second projection 100 a configured to be manipulated by the twisting unit 38.

A rear end portion of the link member 106 is fixed to the second shaft 104. The link member 106 is rotatable about the second shaft 104. A front end portion of the link member 106 is fixed to the second cutter 96 via the connection pin 114.

The torsion spring 108 is attached to the first shaft 102. One end of the torsion spring 108 is in contact the second shaft 104. The fixation pin 115 is fixed to the base member 92, and the other end of the torsion spring 108 is in contact the fixation pin 115. The torsion spring 108 biases the second shaft 104 forward.

As illustrated in FIG. 7 , before the cutter unit 36 cuts the wire W, the second shaft 104 is positioned forward of the first shaft 102. When the second projection 100 a is manipulated forward, the second shaft 104 moves rearward and the link member 106 moves rearward along with the second shaft 104, as illustrated in FIG. 8 . As a result, the second cutter 96 rotates in the third direction D3 (see FIG. 7 ), and thus the wire W is cut.

As illustrated in FIG. 9 , the twisting unit 38 comprises a twist motor 116, a reducer 118, and a holding part 120. The twist motor 116 and the reducer 118 are supported by the body housing 14 (see FIG. 3 ). The twist motor 116 operates using electric power supplied from the battery pack B (see FIG. 3 ). The twist motor 116 is, for example, a brushless motor. The twist motor 116 is controlled by the control circuit board 30 (see FIG. 3 ). The reducer 118 reduces a rotational speed of the twist motor 116 and transmits it to the holding part 120.

The holding part 120 comprises a sleeve unit 122 and a holding unit 124. The sleeve unit 122 comprises a screw shaft 126 (see FIG. 10 ), a ball 128 (see FIG. 10 ), a sleeve 130, and a push plate 132.

The screw shaft 126 illustrated in FIG. 10 rotates with the rotation of the twist motor 116 (see FIG. 9 ). The screw shaft 126 is inserted in the sleeve 130 (see FIG. 9 ). A ball groove 134 is defined in an outer circumferential surface of the screw shaft 126. The ball groove 134 helically extends in the front-rear direction. The ball 128 is retained within the ball groove 134 so as to be movable in the ball groove 134. A ball holding hole (not illustrated) is defined in an inner surface of the sleeve 130 (see FIG. 9 ), and the ball 128 is rotatably retained in the ball holding hole.

As illustrated in FIG. 9 , the push plate 132 is fixed to the sleeve 130. The push plate 132 is positioned near a rear end of the sleeve 130.

The holding unit 124 is inserted in the sleeve 130 from a front end of the sleeve 130. The holding unit 124 comprises a shaft member 136, a left holding member 138, and a right holding member 140. In an initial state which is before the rebar tying tool 2 ties the rebars R, a left wire passage 142 is defined between the shaft member 136 and the left holding member 138 and a right wire passage 144 is defined between the shaft member 136 and the right holding member 140. The left wire passage 142 and the right wire passage 144 allow the wire W to pass therethrough.

Operations of the cutter unit 36 and the twisting unit 38 will be described. When the twist motor 116 rotates in a fourth direction D4, the screw shaft 126 (see FIG. 10 ) rotates along therewith and the ball 128 (see FIG. 10 ) moves within the ball groove 134 (see FIG. 10 ). This causes the sleeve 130 to move forward with respect to the screw shaft 126 and the right holding member 140 to move leftward toward the shaft member 136. As a result, the right wire passage 144 is narrowed and the wire W is clamped at a first position near the tip end of the wire W, between the shaft member 136 and the right holding member 140. When the twist motor 116 further rotates in the fourth direction D4 after the diameter of the loop of the wire W around the rebars R has been reduced, the sleeve 130 moves further forward with respect to the screw shaft 126 and the left holding member 138 moves rightward toward the shaft member 136. As a result, the left wire passage 142 is narrowed and the wire W is clamped at a second position that is closer to the reel 24 (see FIG. 3 ) than the first position is, between the shaft member 136 and the left holding member 138. As illustrated in FIG. 8 , when the twist motor 116 further rotates in the fourth direction D4, the sleeve 130 moves further forward with respect to the screw shaft 126 and the push plate 132 pushes the second projection 100 a of the second lever member 100 forward. This causes the second shaft 104 to move rearward and thus the link member 106 to move rearward. As a result, the second cutter 96 rotates in the third direction D3 (see FIG. 7 ) and the wire W is thereby cut. Once the ball 128 reaches a front end of the ball groove 134 as a result of the twist motor 116 further rotating in the fourth direction D4 shown in FIG. 9 , the sleeve 130 rotates along with the screw shaft 126. The wire W is thereby twisted. When the twist motor 116 rotates in a fifth direction D5 opposite to the fourth direction D4 after the wire W has been twisted, the sleeve 130 moves rearward with respect to the screw shaft 126 and also rotates along with the screw shaft 126. When the sleeve 130 moves rearward with respect to the screw shaft 126, the push plate 132 pushes the first projection 98 a of the first lever member 98 rearward. This causes the second shaft 104 to move forward as illustrated in FIG. 7 , and thus the cutter unit 36 returns to its initial position.

During a tying operation in which the rebar tying tool 2 illustrated in FIG. 1 ties the rebars R with the wire W, various components contact the wire W, and pairs of components move relative to each other while maintaining their contact. In order to reduce wear caused by repeated typing operations in the components that contact the wire W and the pairs of components that contact each other, the components that contact the wire W and the pairs of components that contact each other have high hardness.

The components that contact the wire W include, for example, the first feed gear 58 (see FIG. 4 ), the second feed gear 60 (see FIG. 4 ), the first upper curl guide 70 (see FIG. 6 ), the second upper curl guide 72 (see FIG. 6 ), the third upper curl guide 74 (see FIG. 6 ), the front guide pin 76 (see FIG. 6 ), the first cutter 94 (see FIG. 5 ), the second cutter 96 (see FIG. 5 ), the shaft member 136 (see FIG. 9 ), the left holding member 138 (see FIG. 9 ), and the right holding member 140 (see FIG. 9 ). Hereinafter, the above-listed components that contact the wire W will be simply termed contact members 150.

The pairs of components that contact each other include, for example, the first feed gear 58 (see FIG. 4 ) and the second feed gear 60 (see FIG. 4 ); the first cutter 94 (see FIG. 5 ) and the second cutter 96 (see FIG. 5 ); the first lever member 98 (see FIG. 7 ) and the first shaft 102 (see FIG. 7 ); the second lever member 100 (see FIG. 7 ) and the first shaft 102 (see FIG. 7 ); the second shaft 104 (see FIG. 7 ) and the link member 106 (see FIG. 7 ); the link member 106 (see FIG. 7 ) and the connection pin 114 (see FIG. 7 ); the connection pin 114 (see FIG. 7 ) and the second cutter 96 (see FIG. 7 ); the first projection 98 a (see FIG. 7 ) and the push plate 132 (see FIG. 7 ); the second projection 100 a (see FIG. 7 ) and the push plate 132 (see FIG. 7 ); and the ball 128 (see FIG. 10 ) and the ball grooves 134 (see FIG. 10 ). Especially for the pair of the first feed gear 58 and the second feed gear 60, the pair of the first cutter 94 and the second cutter 96, the pair of the first lever member 98 and the first shaft 102, the pair of the second lever member 100 and the first shaft 102, the pair of the second projection 100 a and the push plate 132, and the pair of the ball 128 and the ball groove 134, relatively large forces act on points where these two components contact each other. Hereinafter, such two components that contact each other will be simply termed a first contact member 152 and a second contact member 154.

As illustrated in FIG. 11 , a contact member 150 comprises a base 160 and a surface layer 162. In FIG. 11 , the base 160 and the surface layer 162 are overdrawn in order to aid in understanding structures of the base 160 and the surface layer 162. The base 160 may be constituted of a metal material, a ceramic material, or a resin material. The base 160 may be an ingot steel base, a steel base produced by precision casting, or a steel base produced by powder metallurgy. The ingot steel base may include, for example, alloy tool steels (SKS, SKD, SKT, SKH), high-speed tool steels (SKH), chrome steels (SCR), chrome molybdenum steels (SCM), nickel-chrome steels (SNC), and nickel-chrome-molybdenum steels (SNC). The steel base produced by precision casting may be produced, for example, by lost-wax process. The steel base produced by powder metallurgy may be produced, for example, by MIM using powder of a high-speed tool steel (HSS powder) as a raw material. Further, the steel base produced by powder metallurgy may be a high-speed tool steel (SKH) or an alloy tool steel (SKD). Hardness of the base 160 may for example be equal to or more than 400 HV, equal to or more than 500 HV, equal to or more than 600 HV, equal to or more than 700 HV, or equal to or more than 800 HV. Herein, HV represents Vickers hardness. This configuration can suppress damage on the base 160 even under repeated tying operations. Further, the hardness of the base 160 may for example be equal to or less than 1000 HV, equal to or less than 900 HV, or equal to or less than 800 HV. This configuration can reduce difficulty in producing (processing) the base 160.

The surface layer 162 constitutes at least a part of an outer surface of the contact member 150, for example, the entire outer surface of the contact member 150. The surface layer 162 covers at least a part of a surface of the base 160, for example, the entire surface of the base 160. In the case where the surface layer 162 covers only a part of the surface of the base 160, the surface layer 162 is arranged at a region that contacts the wire W during the tying operation. The region that contacts the wire W includes, for example, the groove 58 a of the first feed gear 58, the groove 60 a of the second feed gear 60, the left surface 70 b of the first upper curl guide 70, the lower surface 72 a of the second upper curl guide 72, the right surface 74 b of the third upper curl guide 74, a side surface of the front guide pin 76, the first cutter opening 110 of the first cutter 94, the second cutter opening 112 of the second cutter 96, a side surface of the shaft member 136, a front portion of the left holding member 138 that clamps the wire W, and a front portion of the right holding member 140 that clamps the wire W.

As an example, the surface layer 162 of the first feed gear 58 is described with reference to FIGS. 12 and 13 . In the first feed gear 58, the surface layer 162 is formed in the groove 58 a having a V-shape. That is, the groove 58 a is overlayed with the high hardness material. The surface layer 162 is not formed at portions of the first feed gear 58 other than the groove 58 a, such as its outer circumferential surface and side surfaces excluding the groove 58 a, and thus the base 160 is exposed at these portions. In the first feed gear 58, the surface layer 162 is formed only at the portion that contacts the wire W, and thus the overlay (formation of the surface layer 162), which is an expensive process, is effectively performed.

The surface layer 162 illustrated in FIG. 11 is constituted of a high hardness material. The surface layer 162 may be constituted of a metal material or a ceramic material. The surface layer 162 may be constituted of a ceramic material in terms of high hardness, low thermal expansion, and wear resistance. The surface layer 162 is constituted of a material that mainly contains a cemented carbide alloy such as tungsten carbide, and this material may contain a minute amount of other element(s) other than tungsten carbide. The content percentage by weight of tungsten carbide in the material may for example be equal to or more than 80%, equal to or more than 90%, equal to or more than 95%, equal to or more than 96%, equal to or more than 97%, equal to or more than 98%, equal to or more than 99%, or such as 100%. The surface layer 162 is constituted of, for example, a high-speed steel or powder of a high-speed steel.

Hardness of the surface layer 162 is higher than the hardness of the base 160. The hardness of the surface layer 162 may for example be equal to or more than 800 HV, equal to or more than 900 HV, equal to or more than 1000 HV, equal to or more than 1100 HV, or equal to or more than 1200 HV. This configuration can reduce wear of the surface layer 162 even under repeated tying operations. In case of using a wire W with large diameter of 1.6 mm or more, the hardness of the surface layer 162 may be equal to or more than 900 HV. This configuration can reduce wear of the surface layer 162 even when the wire W with large diameter of 1.6 mm or more is used. In order to further reduce wear of the surface layer 162, the hardness of the surface layer 162 may be equal to or more than 1000 HV.

A thickness L1 of the surface layer 162 may for example be equal to or more than 10 micrometers, equal to or more than 15 micrometers, equal to or more than 20 micrometers, equal to or more than 30 micrometers, or equal to or more than 50 micrometers. This configuration can reduce wear of the surface layer 162 even under repeated tying operations. In case of using the wire W with large diameter of 1.6 mm or more, the thickness L1 of the surface layer 162 may be equal to or more than 30 micrometers. This configuration can reduce wear of the surface layer 162 even when the wire W with a large diameter of 1.6 mm or more is used. Further, the thickness L1 of the surface layer 162 may be equal to or more than 50 micrometers.

The thickness L1 of the surface layer 162 may for example be equal to or less than 400 micrometers, equal to or less than 300 micrometers, equal to or less than 200 micrometers, equal to or less than 100 micrometers, equal to or less than 80 micrometers, or equal to or less than 60 micrometers. This configuration can suppress separation of the surface layer 162 from the base 160. In case of using the wire W with a large diameter of 1.6 mm or more, the thickness L1 of the surface layer 162 may be equal to or less than 200 micrometers. This configuration can suppress separation of the surface layer 162 from the base 160 due to repeated tying operations even when the wire W with a large diameter of 1.6 mm or more is used. In order to further suppress the separation of the surface layer 162 from the base 160, the thickness L1 of the surface layer 162 may be equal to or less than 100 micrometers.

The surface layer 162 is formed on the surface of the base 160, for example, by thermal spraying. Specifically, a covering material (e.g., covering material in the form of powder), which is a raw material of the surface layer 162, is heated and the melted covering material is sprayed onto the surface of the base 160. The surface layer 162 is formed on the surface of the base 160 by the melted covering material solidifying on the surface of the base 160. The base 160 is thereby overlayed. In case where the base 160 is constituted of a metal material or a ceramic material, the surface of the base 160 can be suppressed from melting when the melted covering material is sprayed onto the surface of the base 160. Further, in case where the surface of the base 160 is roughened in advance, the melted covering material enters recesses in the surface of the base 160, and thus the separation of the surface layer 162 from the base 160 can further suppressed.

The method of forming the surface layer 162 on the surface of the base 160 may include various methods other than thermal spraying, such as laser cladding and PTA. In case of using laser cladding and PTA, a covering material (e.g., material of covering material), which is a raw material of the surface layer 162, and the surface of the base 160 are heated and melted while the covering material is sprayed toward the surface of the base 160. The surface layer 162 is formed on the surface of the base 160 by the surfaces of the covering material and the base 160 solidifying. The base 160 is thereby overlayed.

As illustrated in FIG. 14 , each of a first contact member 152 and a second contact member 154 comprises a base 170 and a surface layer 172. Characteristics of the material and hardness of the base 170 are the same as the characteristics of the material and hardness of the base 160.

The surface layer 172 of the first contact member 152 constitutes at least a part of an outer surface of the first contact member 152, and the surface layer 172 of the second contact member 154 constitutes at least a part of an outer surface of the second contact member 154. For example, the surface layers 172 constitute the entire outer surfaces of the first contact member 152 and the second contact member 154. The surface layers 172 cover at least a part of surfaces of corresponding bases 170, for example, the entire surfaces of the bases 170. In case where the surface layers 172 cover at least a part of the surfaces of the bases 170, the surface layers 172 are arranged at regions where the first contact member 152 and the second contact member 154 contact each other (regions on the first contact member 152 and the second contact member 154). The regions where the first contact member 152 and the second contact member 154 contact each other include, for example, for the combination of the first feed gear 58 and the second feed gear 60, the outer circumferential surface of the first feed gear 58 and the outer circumferential surface of the second feed gear 60 where the first feed gear 58 and the second feed gear 60 mesh with each other; for the combination of the first cutter 94 and the second cutter 96, the outer circumferential surface of the first cutter 94 and the inner circumferential surface of the second cutter 96; for the combination of the first lever member 98 and the first shaft 102, the inner circumferential surface of the first lever member 98 and the outer circumferential surface of the first shaft 102; for the combination of the second lever member 100 and the first shaft 102, the inner circumferential surface of the second lever member 100 and the outer circumferential surface of the first shaft 102; for the combination of the second shaft 104 and the link member 106, the outer circumferential surface of the second shaft 104 and the inner circumferential surface of the link member 106; for the combination of the link member 106 and the connection pin 114, the inner circumferential surface of the link member 106 and the outer circumferential surface of the connection pin 114; for the combination of the connection pin 114 and the second cutter 96, the outer circumferential surface of the connection pin 114 and the inner circumferential surface of the second cutter 96; for the combination of the first projection 98 a and the push plate 132, a surface of the projection 98 a and the rear surface of the push plate132; for the combination of the second projection 100 a and the push plate 132, the surface of the second projection 100 a and the front surface of the push plate 132; and for the combination of the ball 128 and the ball groove 134, the surface of the ball 128 and the surface of the ball groove 134.

Characteristics of the material of the surface layers 172 are the same as the characteristics of the material of the surface layer 162. Hardness of the surface layers 172 is higher than hardness of the bases 170. The hardness of the surface layers 172 may for example be equal to or more than 800 HV, equal to or more than 900 HV, equal to or more than 1000 HV, equal to or more than 1100 HV, or equal to or more than 1200 HV. This configuration can reduce wear of the surface layers 172 when the surface layer 172 of the first contact member 152 moves in a sixth direction D6 with respect to the surface layer 172 of the second contact member 154. In case where the first contact member 152 and the second contact member 154 are configured such that a relatively large force acts on their surface layers 172, the hardness of the surface layers 172 may be equal to or more than 900 HV. This can reduce wear of the surface layers 172 even when a relatively large force acts on the surface layers 172. In order to further reduce wear of the surface layers 172, the hardness of the surface layers 172 may be equal to or more than 1000 HV.

A thickness L2 of the surface layer 172 of the first contact member 152 may be the same as or different from a thickness L3 of the surface layer 172 of the second contact member 154. The thicknesses L2, L3 of the surface layers 172 are equal to or more than 10 micrometers, equal to or more than 15 micrometers, equal to or more than 20 micrometers, equal to or more than 30 micrometers, or equal to or more than 50 micrometers. This configuration can reduce wear of the surface layers 172 even under repeated tying operations. In case where the first contact member 152 and the second contact member 154 are configured such that a relatively large force acts on their surface layers 172, the thicknesses L2, L3 of the surface layers 172 may be equal to or more than 30 micrometers. This can reduce wear of the surface layers 172 even when a relatively large force acts on the surface layers 172. Further, the thicknesses L2, L3 of the surface layers 172 may be equal to or more than 50 micrometers.

The thicknesses L2, L3 of the surface layers 172 are equal to or less than 400 micrometers, equal to or less than 300 micrometers, equal to or less than 200 micrometers, equal to or less than 100 micrometers, equal to or less than 80 micrometers, or equal to or less than 60 micrometers. This configuration can suppress separation of the surface layers 172 from the bases 170. In case where the first contact member 152 and the second contact member 154 are configured such that a relatively large force acts on their surface layers 172, the thicknesses L2, L3 of the surface layers 172 may be equal to or less than 200 micrometers. This can suppress separation of the surface layers 172 from the bases 170 even when a relatively large force acts on the surface layers 172. In order to further suppress separation of the surface layers 172 from the bases 170, the thicknesses L2, L3 of the surface layers 172 may be equal to or less than 100 micrometers.

The surface layers 172 are formed on the surfaces of the bases 170 by thermal spraying. The method of forming the surface layers 172 on the surfaces of the bases 170 may include various methods other than thermal spraying, such as laser cladding and PTA.

In a modification, each of the contact member 150, the first contact member 152, and the second contact member 154 is constituted of a single material. In each of the contact member 150, the first contact member 152, and the second contact member 154, the base and the surface layer have the same material property (are constituted of the same material). Each of the contact member 150, the first contact member 152, and the second contact member 154 is constituted of a high hardness material. Each of the contact member 150, the first contact member 152, and the second contact member 154 may be constituted of a metal material or a ceramic material. In terms of high hardness, low thermal expansion, and wear resistance, each of the contact member 150, the first contact member 152, and the second contact member 154 may be constituted of a ceramic material. Each of the contact member 150, the first contact member 152, and the second contact member 154 is constituted of a material that mainly contains a cemented carbide alloy such as tungsten carbide, and this material may contain a minute amount of other element(s) other than tungsten carbide. The content percentage by weight of tungsten carbide in the material is equal to or more than 80%, equal to or more than 90%, equal to or more than 95%, equal to or more than 96%, equal to or more than 97%, equal to or more than 98%, equal to or more than 99%, or such as 100%. Each of the contact member 150, the first contact member 152, and the second contact member 154 is constituted of, for example, a high-speed steel or powder of a high-speed steel.

The hardnesses of the contact member 150, the first contact member 152, and the second contact member 154 (e.g., the hardnesses of their surface layers) are equal to or more than 800 HV, equal to or more than 900 HV, equal to or more than 1000 HV, equal to or more than 1100 HV, or equal to or more than 1200 HV. This configuration can reduce wear of the contact member 150, the first contact member 152, and the second contact member 154 even under repeated tying operations. The hardnesses of the contact member 150, the first contact member 152, and the second contact member 154 (e.g., the hardnesses of their surface layers) may be equal to or more than 900 HV. This configuration can reduce wear of the contact member 150, the first contact member 152, and the second contact member 154 even when the wire W with a large diameter of 1.6 mm or more is used and/or even when a relatively large force acts on the first contact member 152 and the second contact member 154. In order to further reduce the wear, the hardnesses of the contact member 150, the first contact member 152, and the second contact member 154 (e.g., the hardnesses of their surface layers) may be equal to or more than 1000 HV.

As an example, the first feed gear 58 and the second feed gear 60 are described with reference to FIG. 15 . Each of the first feed gear 58 and the second feed gear 60 may be manufactured using a single material, for example, powder of a high-speed steel. That is, the base and surface layer of the first feed gear 58 (the second feed gear 60) have the same material property (are constituted of the same material). In this instance, the hardness of the surface layer of the first feed gear 58 (the second feed gear 60), for example, the hardness thereof in the groove 58 a (the groove 60 a), may be equal to or more than 1000 HV. This can reduce wear of the first feed gear 58 (the second feed gear 60). In order to further reduce the wear, the hardness of the surface layer of the first feed gear 58 (the second feed gear 60), for example, the hardness thereof in the groove 58 a (the groove 60 a), may be equal to or more than 1100 HV or equal to or more than 1200 HV.

(Effect)

The rebar tying tool 2 according to the present embodiment is configured to tie the rebars R with the wire W. The rebar tying tool 2 comprises a contact member 150 configured to contact the wire W during the tying operation in which the rebar tying tool 2 ties the rebars R with the wire W. The contact member 150 comprises the base 160; and the surface layer 162 covering at least a part of the surface of the base 160 and configured to contact the wire W during the tying operation. The hardness of the surface layer 162 is higher than the hardness of the base 160.

According to the configuration above, the hardness of the surface layer 162 is higher than the hardness of the base 160, and thus the surface layer 162 of the contact member 150 is less likely to wear out when contacting the wire W, as compared with a configuration in which the contact member 150 comprises only the base 160. Thus, wear of the contact member 150 can be reduced even under repeated tying operations.

Further, the surface layer 162 is constituted of a ceramic material.

Generally, ceramic materials have higher hardness compared with other materials. According to the configuration above, wear of the contact member 150 can be further reduced even under repeated tying operations.

Further, the ceramic material includes tungsten carbide.

Generally, tungsten carbide has higher hardness compared with other materials. According to the configuration above, wear of the contact member 150 can be further reduced even under repeated tying operations.

Further, the thickness L1 of the surface layer 162 is equal to or more than 10 micrometers.

If the thickness L1 of the surface layer 162 is less than 10 micrometers, the surface layer 162 may be damaged by a force it receives from the wire W. According to the configuration above, it is possible to suppress the surface layer 162 from being damaged by the force it receives from the wire W.

Further, the thickness L1 of the surface layer 162 is equal to or less than 200 micrometers.

According to the configuration above, separation of the surface layer 162 from the base 160 can be suppressed even under repeated tying operations.

Further, the hardness of the surface layer 162 is equal to or more than 900 HV.

Generally, the contact member 150 is likely to wear out with the use of a wire W having a larger diameter. According to the configuration above, wear of the contact member 150 can be further reduced even when a large-diameter wire W is used.

Further, the rebar tying tool 2 further comprises the feed motor 50; and the first feed gear 58 or the second feed gear 60 (an example of feed roller) configured to rotate with rotation of the feed motor 50 and feed the wire W toward the rebars R. The contact member 150 forms the first feed gear 58 or the second feed gear 60.

Generally, the first feed gear 58 and the second feed gear 60 are likely to wear out because they feed the wire W toward rebars R. According to the configuration above, wear of the first feed gear 58 or the second feed gear 60 can be reduced even under repeated tying operations.

Further, the rebar tying tool 2 further comprises the first cutter 94 or the second cutter 96 (an example of cutter) configured to cut the wire W during the tying operation. The contact member 150 forms the first cutter 94 or the second cutter 96.

Generally, the first cutter 94 and the second cutter 96 are likely to wear out because they are pressed hard against the wire W to cut it. According to the configuration above, wear of the first cutter 94 or the second cutter 96 can be reduced even under repeated tying operations.

The rebar tying tool 2 according to the present embodiment is configured to tie the rebars R with the wire W. The rebar tying tool 2 comprises a first contact member 152; and a second contact member 154 configured to contact the first contact member 152 and move relative to the first contact member 152 during the tying operation in which the rebar tying tool 2 ties the rebars R with the wire W. The first contact member 152 comprises the base 170 (an example of first base); and the surface layer 172 (an example of first surface layer) covering at least a part of the surface of the base 170. The second contact member 154 comprises the base 170 (an example of second base); and the surface layer 172 (an example of second surface layer) covering at least a part of the surface of the base 170 and configured to contact the surface layer 172 of the first contact member 152 during the tying operation. The hardness of the surface layer 172 of the first contact member 152 is higher than the hardness of the base 170 of the first contact member 152. The hardness of the surface layer 172 of the second contact member 154 is higher than the hardness of the base 170 of the second contact member 154.

According to the configuration above, the hardness of the surface layer 172 of the first contact member 152 is higher than the hardness of the base 170 of the first contact member 152 and the hardness of the surface layer 172 of the second contact member 154 is higher than the hardness of the base 170 of the second contact member 154, and thus the surface layer 172 of the first contact member 152 and the surface layer 172 of the second contact member 154 are less likely to wear out when rubbing against each other, as compared with a configuration in which the first contact member 152 comprises only the base 170 and the second contact member 154 comprises only the base 170. Thus, wear of the first and second contact members 152, 154 can be reduced even under repeated tying operations.

Further, each of the surface layer 172 of the first contact member 152 and the surface layer 172 of the second contact member 154 are constituted of a ceramic material.

Generally, ceramic materials have higher hardness compared with other materials. According to the configuration above, wear of the first and second contact members 152, 154 can be further reduced even under repeated tying operations.

Further, the ceramic material includes tungsten carbide.

Generally, tungsten carbide has higher hardness compared with other materials. According to the configuration above, wear of the first and second contact members 152, 154 can be further reduced even under repeated tying operations.

Further, each of the thickness L2 of the surface layer 172 of the first contact member 152 and the thickness L3 of the surface layer 172 of the second contact member 154 is equal to or more than 10 micrometers.

If each of the thickness L2 of the surface layer 172 of the first contact member 152 and the thickness L3 of the surface layer 172 of the second contact member 154 is less than 10 micrometers, the surface layers 172 of the first and second contact members 152, 154 may be damaged by them contacting each other during the tying operation. According to the configuration above, it is possible to suppress the surface layers 172 of the first and second contact members 152, 154 from being damaged.

Further, each of the thickness L2 of the surface layer 172 of the first contact member 152 and the thickness L3 of the surface layer 172 of the second contact member 154 is equal to or less than 200 micrometers.

According to the configuration above, separation of the surface layer 172 of the first contact member 152 from the base 170 of the first contact member 152 and separation of the surface layer 172 of the second contact member 154 from the base 170 of the second contact member 154 can be suppressed even under repeated tying operations.

Further, each of the hardness of the surface layer 172 of the first contact member 152 and the hardness of the surface layer 172 of the second contact member 154 is equal to or more than 900 HV.

Generally, a larger force acts between the first and second contact members 152, 154 with use of a wire W having a larger diameter. According to the configuration above, wear of the first and second contact members 152, 154 can be further reduced even when a large-diameter wire W is used.

Further, the rebar tying tool 2 further comprises the cutter unit 36 configured to cut the wire W during the tying operation. The cutter unit 36 comprises the first cutter 94 (an example of first contact member) and the second cutter 96 (an example of second contact member).

The cutter unit 36 is pressed hard against the wire W to cut it, and thus a large force acts between the first and second cutters 94, 96. Therefore, the first and second cutters 94, 96 of the cutter unit 36 are likely to wear out in general. According to the configuration above, wear of the first and second cutters 94, 96 can be reduced even under repeated tying operations.

The rebar tying tool 2 according to the present embodiment is configured to tie the rebars R with the wire W. The rebar tying tool 2 comprises the first feed gear 58 or the second feed gear 60 (an example of feed roller) configured to feed the wire W toward the rebars R when the rebar tying tool 2 ties the rebars R with the wire W. The hardness of the surface layer 162 of the first feed gear 58 or the second feed gear 60 is equal to or more than 900 HV.

The first feed gear 58 and the second feed gear 60 contact the wire W when feeding the wire W toward the rebars R. According to the configuration above, the hardness of the surface layer 162 of the first feed gear 58 or the second feed gear 60 is equal to or more than 900 HV, and thus the surface layer 162 of the first feed gear 58 or the second feed gear 60 is less likely to wear out when contacting the wire W. Thus, wear of the first feed gear 58 or the second feed gear 60 can be reduced even under repeated tying operations.

The rebar tying tool 2 according to the present embodiment is configured to tie the rebars R with the wire W. The rebar tying tool 2 comprises the first feed gear 58 (an example of first feed roller) configured to contact the wire W and be rotated by the feed motor 50 (an example of motor) when the wire W is fed toward the rebars R; and the second feed gear 60 (an example of second feed roller) configured to contact the wire W when the wire W is fed toward the rebars R. The wire W is clamped between the first feed gear 58 and the second feed gear 60 and fed toward the rebars R by rotation of the first feed gear 58. The first feed gear 58 comprises the groove 58 a that the wire W passes through when the wire W is fed toward the rebars R. The hardness of the first feed gear 58 in the groove 58 a is equal to or more than 1000 HV.

According to the configuration above, the hardness of the first feed gear 58 in the groove 58 a is equal to or more than 1000 HV, and thus the first feed gear 58 is less likely to wear out when contacting the wire W in the groove 58 a. Thus, wear of the first feed gear 58 in the groove 58 a can be reduced even under repeated tying operations. 

What is claimed is:
 1. A rebar tying tool configured to tie rebars with a wire, the rebar tying tool comprising: a contact member configured to contact the wire during a tying operation in which the rebar tying tool ties the rebars with the wire, wherein the contact member comprises: a base; and a surface layer covering at least a part of a surface of the base and configured to contact the wire during the tying operation, and hardness of the surface layer is higher than hardness of the base.
 2. The rebar tying tool according to claim 1, wherein the surface layer is constituted of a ceramic material.
 3. The rebar tying tool according to claim 2, wherein the ceramic material includes tungsten carbide.
 4. The rebar tying tool according to claim 1, wherein a thickness of the surface layer is equal to or more than 10 micrometers.
 5. The rebar tying tool according to claim 4, wherein the thickness of the surface layer is equal to or less than 200 micrometers.
 6. The rebar tying tool according to claim 1, wherein the hardness of the surface layer is equal to or more than 900 HV.
 7. The rebar tying tool according to claim 1, further comprising: a feed motor; and a feed roller configured to rotate with rotation of the feed motor and feed the wire toward the rebars, wherein the contact member forms the feed roller.
 8. The rebar tying tool according to claim 1, further comprising a cutter configured to cut the wire during the tying operation, wherein the contact member forms the cutter.
 9. A rebar tying tool configured to tie rebars with a wire, the rebar tying tool comprising: a first contact member; and a second contact member configured to contact the first contact member and move relative to the first contact member during a tying operation in which the rebar tying tool ties the rebars with the wire, wherein the first contact member comprises: a first base; and a first surface layer covering at least a part of a surface of the first base, the second contact member comprises: a second base; and a second surface layer covering at least a part of a surface of the second base and configured to contact the first surface layer during the tying operation, hardness of the first surface layer is higher than hardness of the first base, and hardness of the second surface layer is higher than hardness of the second base.
 10. The rebar tying tool according to claim 9, wherein each of the first surface layer and the second surface layer is constituted of a ceramic material.
 11. The rebar tying tool according to claim 10, wherein the ceramic material includes tungsten carbide.
 12. The rebar tying tool according to claim 9, wherein each of a thickness of the first surface layer and a thickness of the second surface layer is equal to or more than 10 micrometers.
 13. The rebar tying tool according to claim 12, wherein each of the thickness of the first surface layer and the thickness of the second surface layer is equal to or less than 200 micrometers.
 14. The rebar tying tool according to claim 9, wherein each of the hardness of the first surface layer and the hardness of the second surface layer is equal to or more than 900 HV.
 15. The rebar tying tool according to claim 9, further comprising a cutter unit configured to cut the wire during the tying operation, wherein the cutter unit comprises the first contact member and the second contact member.
 16. A rebar tying tool configured to tie rebars with a wire, the rebar tying tool comprising: a feed roller configured to feed the wire toward the rebars when the rebar tying tool ties the rebars with the wire, wherein hardness of a surface layer of the feed roller is equal to or more than 900 HV.
 17. A rebar tying tool configured to tie rebars with a wire, the rebar tying tool comprising: a first feed roller configured to contact the wire and be rotated by a motor when the wire is fed toward the rebars; and a second feed roller configured to contact the wire when the wire is fed toward the rebars, wherein the wire is clamped between the first feed roller and the second feed roller and fed toward the rebars by rotation of the first feed roller, the first feed roller comprises a groove that the wire passes through when the wire is fed toward the rebars, and hardness of the first feed roller in the groove is equal to or more than 1000 HV. 